CH640325A5 - Butterfly valve. - Google Patents

Description

640,325

2

CLAIMS (9) whose axis (Y-Y) meets the flow axis (X-X) and

1. Butterfly valve, comprising a tubular body which is connected to rotational drive means.

delimits a flow conduit and a shut-off butterfly 15. Butterfly valve according to one of claims 1 to

rotatably mounted in this body about an axis perpendicular to 13, characterized in that the butterfly (8b) is keyed on an ar-axis of the conduit, one of the two elements carrying a 5 bre gasket (9b) whose the axis (ZZ) does not meet the elastic sealing flow axis and the other a seat surface for this (XX) and which pivots freely in the body (lb), in a packing, the packing d sealing having a line to constitute a non-return valve.

identical to the center line of the seat, to the crush- 16. Butterfly valve according to one of claims 1 to

ment close to the lining, characterized in that at each point 15, characterized in that the seat (5) is foundry rough.

from the center line of the seat, the tangent plane (T) to the seat 10

forms an acute angle (x) at least approximately constant with the

The tangent (Mt) to the trajectory of the corresponding point (M) of the butterfly (8) at the point of contact of the gasket (13) with the present invention relates to a seat butterfly valve. comprising a tubular body which delimits a duct

2. Butterfly valve according to claim 1, flow characteristic and a shutter butterfly rotatably mounted in this riser in that said angle (x) is 20 to 30 °. body around an axis perpendicular to the axis of the duct, one

3. Butterfly valve according to one of claims 1 and of the two elements carrying an elasti-2 seal, characterized in that the seal line (16) defined on that and the other a seat surface for this packing, the gar-body (1) present in section through the plane containing the axis (XX) niture presenting a sealing line identical to the line of the flow conduit (3) and perpendicular to the axis of rota-20 of the seat, crushing near the upholstery.

tion (YY) of the butterfly (8), this plane being a plane of symmetry In these taps, the gasket can be accommodated for the tap, a half-amphora profile having either Either in the body, or on the butterfly. In addition, the axis of rota-side of the flow axis, from its end (A), a tion of the butterfly can either meet the flow axis (pa-part inclined approximately rectilinear ( 17) corresponding to the centered butterfly foot), or not to meet it (eccentric butterfly), of the amphora and connecting to a belly (18) whose top 25 The problem of the tightness of a butterfly valve (19 ) is rounded and convex and located outside the flow axis, consists in obtaining a good peripheral contact between the trim and, on the other side of this axis (XX), a concave part (20) ture and the seat in closed position, especially in the corresponding to the neck of the amphora. diametral zone close to the axis of rotation. This problem is

4. Butterfly valve according to claim 3, character- usually resolved (see for example the FR patent laughed in that the ends (A, B) of the profile in half-amphora so 1,543,451) by providing a significant interference between the are aligned with the trace (0) of the axis of rotation (YY) on the seat and the lining, that is to say a radial projection relative to said plane. important of the seal compared to the

5. Butterfly valve according to one of claims 1 on the surface of the seat.

4, with a seal carried by the butterfly, characterized, however, this interference leads to friction in that the seal (13) is constituted by a large protuberance 35 in the vicinity of the closed position, and therefore of a elastomeric coating (14) covering the whole in addition to heavy wear of the seal, to a butterfly (8), the crest of this protuberance forming the line torque and high power required to sealing (15) of the butterfly (8). to rotate the butterfly.

6. Butterfly valve according to one of claims 1 to Because of these drawbacks, the problem arose

5, characterized in that the seat surface (5) is a surface 40 free from the need for any interference or predefined projection. seal finished with respect to the surface

7. Butterfly valve according to claim 6, character of the seat to which it is to be applied.

laughed in that each generator (VV) of the seat surface For this purpose, the invention relates to a butterfly valve (5) is perpendicular to the tangent (Mt) to the line of etan of the aforementioned type, characterized in that at each point of the li-cheity (16) of this surface at the point (M) considered. ^ 45 average seat size, the plane tangent to the seat forms an angle

8. Butterfly valve according to one of claims 1 at acute at least approximately constant with the tangent to the trajec-7, characterized in that said angle (x) is strictly roof from the corresponding point of the butterfly to the point of contact constant over the entire periphery of the butterfly (8) and the seat (5). of the trim with the seat.

9. Butterfly valve according to one of claims 1 to Thanks to this arrangement, the seal is ensured over the whole of 7, characterized in that said angle (x) varies over the entire perimeter of the butterfly by simple compression. or crushing of the throttle valve (8) and the seat (5) due to the progressive progression of the lining. This, as soon as the angle considered radius of displacement of the current point (M) of the line has a sufficient value, approaches or approaches the seat without sealing (15) of the butterfly. slip or friction, even in the diametric zone

10. Butterfly valve according to one of claims 1 to line close to the axis of rotation.

9, characterized in that the face (11) of the butterfly (8) which carries the 55 Thus, not only the wear and the operating torque of the seal (13) on its periphery is curved. are reduced, but the seat may be foundry, being

11. Butterfly valve according to claim 10, charac- of course that the expression "rough casting" does not mean terized in that said curved surface (11) is a cyan surface provided that the surface is coarse because the lindric means with generators parallel to the axis of rotation (YY). ^ current foundry molding allow to realize

12. Butterfly valve according to one of claims 1 to so beautiful surface conditions, for example using sands of 9, characterized in that the surface (11a) of the butterfly (8a) which fine particle size agglomerated by synthetic binders disport the seal (13) on its periphery are commercially available.

hollowed out. The angle considered, which is preferably 20 ° to 30 °, can

13. Butterfly valve according to claim 12, charac- Either be rigorously constant over the entire periphery of the Terérisé in that the recessed surface (1 la) is a cylindrical surface "papiuon and seat, to facilitate manufacture, or vary than generators perpendicular to the axis of rotation (YY). on this periphery in inverse ratio to the radius of displacement

14. Butterfly valve according to one of claims 1 to the current point of the sealing line, to make uni-13, characterized in that the butterfly (8) is keyed on a shaft forms the crushing of the lining in all positions of

3

640,325

throttle closing, even before the maximum closing position is reached.

According to one embodiment of the invention, the sealing line defined on the body has, in section through the plane containing the axis of the flow conduit and perpendicular to the axis of rotation of the butterfly, this plane being a plane of symmetry for the tap, a half-amphora profile comprising on one side of the flow axis, from its end, a roughly rectilinear inclined part corresponding to the foot of the amphora and connecting to a belly whose apex is rounded and convex and situated outside the flow axis, and, on the other side of this axis, a concave part corresponding to the neck of the amphora.

The characteristics and advantages of the invention will emerge from the description which follows, given by way of nonlimiting example and with reference to the appended drawings, in which:

fig. 1 is a view in longitudinal section of a butterfly valve according to the invention, in the closed position;

fig. 2 is a similar view of the butterfly valve of FIG. 1 in the open position;

fig. 3 is a transverse view of the seat and of the butterfly in the open position, taken in the direction of the arrow 3 in FIG. 2;

fig. 4 is a geometric diagram illustrating the geometric definition of the sealing line between the lining and its seat as well as that of the sealing surface

fig. 5 and 6 are diagrams similar to FIG. 4 showing two variants of sealing lines;

fig. 7,8 and 9 are simplified perspective views respectively representing the seat surface alone, the butterfly alone and the assembly of the butterfly and of the seat in the partially open position of the valve;

fig. 10 is a sectional view of a variant of the butterfly of FIG. 1;

fig. 11 is a view along the arrow of the butterfly of FIG. 10;

fig. 12 is a partial view on a large scale illustrating the interference of a butterfly seal and its seat in a tap of the prior art;

fig. 13 and 14 are similar detailed views illustrating the compression of the seal on the seat of the valve of the invention, FIG. 13 showing the packing in the free state when it comes into contact with the seat and FIG. 14 the packing in the compressed state, in the fully closed position;

fig. 15 is a geometric diagram similar to FIGS. 5 and 6 showing two radii of unequal lengths between the sealing line and the axis of rotation of the butterfly;

fig. 16 and 17 are views similar to FIG. 14 illustrating with exaggeration an alternative embodiment of the seat surface with modification of angle between the two spokes of FIG. 15; and fig. 18 is a view similar to FIG. 1 of a variant of a butterfly valve according to the invention, this valve being of the eccentric type and usable as a non-return valve.

According to the embodiment shown in fig. 1 to 3 and 7 to 9, the invention is applied to a controlled butterfly valve whose tubular body 1, of axis XX supposed to be horizontal, is provided with flanges 2 for connection to the pipe on which the valve is to be mounted, these flanges 2 being moreover optional. This valve is applicable to water, petroleum or other liquid pipes as well as pipes carrying gaseous fluids or powdery solid products.

The body 1 has at mid-length, projecting inside the cylindrical flow cavity 3 of circular section, a seat 4 composed of two sides 5 and 6 of uneven slopes which are irregular surfaces evolving continuously around of the axis XX and intersecting along an edge 7 forming an irregular closed loop around this axis XX. The face 5 with a slight slope constitutes the seat proper of the tap. The body is rough foundry, but the seat nevertheless has a good surface condition thanks to the use of a modern process of precision casting in foundry.

The rotary shutter or butterfly 8 is of the "centered" type, that is to say it is keyed onto a rotation shaft 9 of axis YY perpendicular to the axis XX, also assumed to be horizontal and cutting it Ci in 0. The shaft 9 is connected to means 10 for driving in rotation in both directions (not shown). The butterfly 8 comprises a flat face 10 swollen along the axis YY in a cylindrical sector receiving the shaft 9, a convex face 11 connected to the face 10 by the two ends of the latter furthest from the axis YY, and two rounded side faces i5 12 closing the volume of the butterfly and crossed by the shaft 9.

In this example, the axis YY is offset in the sense that it is not located in the plane of the face 10 of the butterfly but offset by a small distance d relative to this plane, on the side of the face 11 opposite.

The entire periphery of the curved face 11 is surrounded by a bead or seal 13 made of elastomer intended to be applied in a sealed manner to the seat 5. In this embodiment, the seal 13 is a protuberance of a cover. -25 tement 14 made of elastomer which is provided with the butterfly assembly 8. This protuberance follows a curved and sinuous contour, closed, and has a small width on either side of a crest or sealing line 15. The cross section of the cord 13 is triangular, the line 15 constituting the apex 30 of this triangle. The average line 16 of the seat 5 is identical to the line 15, except for the crushing of the elastomer, as will be seen below.

In the valve closed position, the seat 4 and the butterfly valve 8 admit as plane of symmetry the plane P 35 (fig. 3) perpendicular to the axis of rotation Y-Y and containing the axis X-X of flow.

Around the entire periphery of the duct, that is to say at any point M of the sealing line 16, the tangent plane T to the sealing surface or seat 5 makes an acute angle x constant or approximately 40 constant with the tangent t to the circle of radius R and of axis YY passing through the point M (fig. 4 and 13). This condition is fulfilled even in the extreme zones close to the Y-Y axis, of trace O.

To define the sealing line 16, refer to Fig. 45. 4, which schematically represents the cylindrical flow conduit 3 and assumes the line 16 drawn on this cylinder.

From an arbitrary point M located on the conduit 3, we draw the tangent Mt to the circle of axis Y-Y passing through M. The tangent plane sought makes a given angle x with the line Mt; so it is therefore a plane T tangent to the cone C with an axis Mt and a half-angle at the vertex x, and the tangent sought Mt1 belongs to this plane. For reasons of bulk of the butterfly perpendicular to the axis Y-Y, we choose, for a given plane T, the line Mt1 formed by the generatrix of the cone C 55 in this plane.

To define the plane T, we notice that the tangent Mt1 also belongs to the tangent plane in M to the conduit 3.

This tangent is therefore finally formed by the intersection (or by one of the intersections) of this tangent plane with the 60 cone C.

By repeating this construction point by point, and taking into account the necessary continuity, we have retained for lines 15 and 16 the half-amphora profile shown in FIGS. 1 and 2. From an extreme point A furthest from the axis es Y-Y in the closed position and constituting the foot of the amphora, this point being the highest in FIG. 1, this profile successively comprises a roughly rectilinear or slightly concave portion 17 moving obliquely away from the flat face 10

640,325

4

(fig. 2), a curved part or belly 18 whose rounded top 19 is close to the axis X-X but located before it,

then, roughly from this axis, a concave part 20 extending to the other extreme point B furthest from the axis Y-Y.

Thus, the line 15 is entirely located on one side of the face 10. The points A and B can either be aligned with the point 0 as in FIGS. 1 and 2, or, as a variant, offset in one direction or the other parallel to the axis X-X as shown in FIGS. 5 and 6. The solution chosen is that which presents the minimum axial bulk, which is to be studied in each particular case.

View in a perpendicular direction, that is to say along the axis XX for the sealing line 15 when the butterfly is in the fully open position, this sealing line has a trough shape with two points d inflection near its ends, as seen in fig. 3.

The starting point M of the curve 16 is chosen relative to the YY axis so that this curve 16 is as advantageous as possible: this choice must lead to a belly 18 whose rounded convex vertex 19 is located the most as close as possible to the YY axis, however leaving the necessary passage for the control shaft 9. For example, it would be irrational to choose a point M too far from the YY axis, making it necessary to dig locally the internal wall of the cavity 3 to allow passage to the radius OM of the butterfly 8 during the movement thereof.

We have seen above that the tangent plane T to the seat surface 5 at point M is defined at the same time as the tangent Mt1 to the sealing line 16. The surface 5 is a regulated surface forming the envelope of all the tangent planes T along line 16. To obtain the generator at point M, we draw in the tangent plane T a short line segment MV, MV 'perpendicular to the line Mt1 and of length L, on both sides from point M. The surface 5 evolves in a sinuous fashion around the axis XX, being turned towards one end of the body 1 at point A situated on one side of the plane defined by the axes XX and YY and towards the other end from body 1 at opposite point B. The inclination of the axis of symmetry 13a of the section of the sealing bead 13 of the butterfly relative to this same plane changes in a similar fashion, so that, at each point of the sealing line, this bead is turned towards the seat 5 at the end of closing the butterfly valve as shown in FIG. 13.

The way in which the packing 13 works is shown in FIGS. 13 and 14: at each point, this lining approaches the seat 5 by its top M (fig. 13), and the continued rotation of the butterfly causes pure compression of the lining, with deformation of the elastomer but without any sliding no friction (fig. 14). This is to be compared with the lining 113 shown in FIG. 12, which belongs to the known butterfly valve described in patent FR 1 543 451: the lining 113 of the butterfly 108 has an interference or overlap e with the seat 105 and approaches the latter laterally, so that, when closing as at opening, its compression is accompanied by significant friction leading to rapid wear.

The angle x formed by the tangent plane T at the surface of the seat at a point M and by the tangent t at the point M at the circle of radius OM, is chosen as a function of the optimal crushing of the seal 13 in elastomer on the seat 5. The term "optimum crushing" means that which is necessary and sufficient around the entire circumference of the throttle valve and of the seat surface to ensure sealing in the closed position of the throttle valve, for a given operating pressure. For an equal nominal diameter of the flow pipe 3, the crushing e necessary for sealing is higher for a higher operating pressure than for a lower operating pressure. To the crushing e is linked the force or the closing torque of the butterfly: this torque is higher for a greater crushing than for a weaker crushing. Thus, the optimal crushing e is that which requires the closing torque just sufficient to ensure the seal.

You can choose a strictly constant angle x over 5 all around the butterfly and the seat surface, which allows an easier realization. You can also choose to vary the angle x along the circumference of the butterfly and the seat surface. In both cases, the crushing e of the elastomeric gasket 13 on the seat 5 is constant 10 over the entire periphery of this seat in the butterfly closed position. But, in the first case, the crushing e is constant only in the maximum closed position, and it varies over the entire periphery between the position of start of docking of the seal on the seat surface and the final closed position. On the contrary, in the second case, it is possible to obtain a constant crushing over the entire periphery from the moment when the lining comes into contact with the seat and up to the final closed position.

More precisely, if a constant angle x is chosen, during the 2o rotation of the butterfly 8 towards its closed position, the docking and the crushing of the seal 13 begin with the points of the seal line 15 closest to the axis of rotation YY and then gradually spread over the entire periphery. Consequently, the value of the crushing of the lining varies over the entire periphery up to the maximum closed position, for which the value e becomes constant over the entire periphery. If you want to limit the tightening force of the butterfly in the closed position, that is to say not to reach the close position ma-30 ximal, you must therefore ensure that, on the points of the circumference where the crushing has the lowest value, this value is sufficient to ensure sealing taking into account the pressure considered.

On the contrary, the angle x can be varied due to the in-35 verse of the radius OM over the entire periphery of the butterfly, that is to say in inverse ratio to the distance between each point M of the sealing line 15 and the center point 0 of the YY axis of rotation. Taking into account the shape of the sealing line 15 in a half-amphora, the radius OM1 is minimal in the vicinity of the axis of rotation YY, and therefore the maximum angle x1 in this area (fig. 17), while the radius OM2 is maximum at the ends of the diameter AB and therefore the minimum angle x2 at these ends (fig. 16). It is thus possible to obtain a simultaneous docking of all the points of the crest of the lining 13 on the seat surface 5 and, from this docking, a uniform value of the crushing of the seal over the entire periphery of the butterfly and of the seat surface, this crushing gradually increasing as the butterfly is tightened on the seat, that is to say when the butterfly rotates, but in 5Q remaining uniform over the entire periphery during this tightening or this rotation. This has the advantage that, when one does not go to the maximum closed position, the seal is certain around the entire periphery as soon as the crushing is sufficient at one point, taking into account the pressure of 55 service. This therefore makes it possible to reduce the clamping force for a given pressure. However, in return, the realization of the sealing line of the seat surface is much more difficult and the axial size is greater, the amphora being more "plump".

60 In practice, it is possible to adopt a constant angle x of the order of 20 to 30 °, admitting variations of a few degrees more or less on certain points of the sealing line 15 in order to soften the variations or the evolution of curvature of the seat surface 5.

65 Geometrically, this amounts to admitting that the tangent Mt1 (fig. 4) is not always exactly located on the cone C but can be located in the vicinity of this cone. In other words, it sometimes gives up the minimum size of the butterfly 8 to seek greater security in the étan-

cheeseness by a better uniformity of the crushing e on the circumference. It should be noted in this regard that, depending on the choice of the angle x (strictly constant over the entire circumference of the butterfly and the seat or admitting slight variations), the prominence of the belly of the half-amphora profile may be more or less accentuated.

In a practical embodiment which has given satisfaction, the seat 4 and the butterfly 8 thus geometrically defined are produced in the following manner.

The seat 4 (fig. 1,3,7 and 9) projects inward from the duct 3 and is located on either side of the plane of symmetry P: the seat surface 5 is a sinuous surface located on the and other of the sealing line 15 in half-amphora. By a more or less progressive twist below the YY axis, on each side of the plane of symmetry P, the seat surface 5 changes orientation from point A to point B to face obliquely to the direction of flow if it was oriented in the opposite direction, or vice versa. On the other hand, at the two ends of the axis YY, the surface 5 has the same orientation with respect to the direction of flow, and this orientation is the same up to point A located on the side of the butterfly in the open position of this one (fig. 3). The surface 5 remains inclined at a constant or approximately constant angle, even in the region of the axis YY of rotation, with respect to the tangent at any point M of the sealing line 15 to the circle of radius OM which is the trajectory traversed by the point M during the rotation of the butterfly 8. This angle is of the order of 20 to 30 °. Said sealing surface 5 bypasses the cavity of the rotation shaft 9 of axis Y-Y and is located on one side thereof, and the same is true of the seal 13 of the butterfly.

In the embodiment of FIGS. 1 to 3 and 7 to 9, the surface 11 of the butterfly 8 opposite the planar face 10 is a curved cylindrical surface with generatrices parallel to the axis Y-Y. Alternatively, as shown in Figs. 10 and 11, this surface 1a can be hollowed out in a trough, with generators roughly perpendicular to the axis YY, the minimum thickness being just sufficient to allow the passage of the shaft 9 of the butterfly 8a (fig. 10 ). In both cases, the butterfly has an aerodynamic or hydrodynamic profile in the fully open position, 90 ° from its closed position, and therefore offers minimal resistance to flow.

As indicated above, during the closing rotation of the butterfly valve 8, the seal 13 approaches the seat 5 and approaches it more or less simultaneously over the entire periphery of the butterfly valve and the seat according to the aforementioned choice of l 'angle x. This docking takes place without sliding or friction but only with compression or progressive crushing of the seal against the seat. In the closed position, this crushing of the seal exists

640,325

all around the throttle and the seat, and on one side of the rotation shaft 9, which is bypassed.

Thus, the closing of the duct 3 is absolutely hermetic and, given the absence of sliding or friction, it takes place with the minimum wear of the seal 13 during the successive operations of the butterfly. Even in the area of the axis of rotation Y-Y, the seal 13 is approached on its seat 5 as is illustrated in FIGS. 13 and 14, and the crest 15 is progressively crushed on the seat, without sliding or friction, during the rotation of the butterfly 8. During this docking, each point of the crest 15 meets a plane tangent to the seat surface 5 having at least approximately the same inclination with respect to the tangent to the circle of rotation of the point considered of the crest 15.

In the variant of FIG. 18, the butterfly 8b has the same shape as the butterfly 8 of FIGS. 1 to 3 and 7 to 9, but it is eccentric: its axis of rotation Z-Z does not meet the axis X-X, while of course remaining orthogonal to it.

More specifically, the neck B of the demiamphore profile is located on the side of the axis of rotation ZZ of the rotation shaft 9b, which pivots freely in the body lb, while the apex 19 of the belly is located on the other side of the flow axis XX. The butterfly 8b is keyed onto the rotation shaft 9b by means of a pair of ears 20 which protrude from the flat face 10.

The neck and the belly of the profile of the butterfly 8b being thus distributed with respect to the axes XX and ZZ, the butterfly is unbalanced voluntarily, so that if the direction of the flow is that of the arrow f, the flow must overcome the tendency of the butterfly 8b to turn under the effect of gravity around the axis ZZ in the direction of the arrow g, that is to say always to return to the closed position, and that, if the direction of the flow is reversed with respect to arrow f, the butterfly 8b closes by turning along arrow g. Consequently, the butterfly valve 8b prohibits the flow in the opposite direction of the arrow f and behaves like a non-return valve.

The geometrical conditions defining the sealing lines 15 and 16 as well as the seat surface 5 are the same as above, and the aforementioned advantages on the closing and sealing conditions are also the same, especially in the area of the eccentric axis of rotation ZZ.

It will be noted that, in this variant, the tubular body 1b is devoid of end flanges. Such a body is intended to be mounted with clamping between two flanges of a pipe connected to each other by tie rods, in a manner known per se.

Of course, all of the above applies to the case where the seat is formed on the periphery of the butterfly and where the elastic lining is carried by the valve body.

5

5

10

15

20

25

30

35

40

45

50

VS

4 sheets of drawings